In such a brake system it is customary to mount a power cylinder on the front side of the dashboard, i.e. within the engine compartment, and to let a hub thereof extend through an aperture in the dashboard in order to facilitate the linking of a control valve in the power cylinder with a brake pedal on the driver's side; see, for example, U.S. Pat. No. 3,222,868. With the power cylinder split into a lid or header adjoining the dashboard and a body or base remote therefrom, the master cylinder of the hydraulic brake system--which is generally of smaller diameter than the power cylinder--can be coaxially attached to that base. It has already been proposed to envelop the two parts of the power cylinder in a basket-like holder with a central flange supporting the master cylinder at its end proximal to the power cylinder, that holder having struts which are bent in axial planes around the periphery of the power cylinder and are anchored to the dashboard; see German laid-open specification No. 28 14 372. The purpose of this holder is to prevent an axial expansion of the power cylinder, in response to a brake-operating pressure applied to the piston of the master cylinder, and thus to avoid a significant displacement of the latter cylinder relative to the dashboard.
In order to achieve this purpose, both the holder and the master cylinder must be made of rigid and correspondingly heavy material designed to withstand the applied braking pressure as reinforced in the power cylinder. Since the holder is not readily adjustable, it must be adapted to the contour of the power cylinder with close tolerances to obviate undesirable variations in the pedal stroke.
It is known, e.g. from German laid-open specifications Nos. 28 30 262 and 28 45 794, to provide a power cylinder of an automotive brake system with at least two axially extending rods anchored to its front and rear walls in order to stabilize their positions, these rods passing through the interior of the power cylinder and penetrating a flexible partition--termed a roll membrane--which divides that interior into two differentially pressurizable chambers. Threaded ends of these rods, projecting from the power cylinder, may serve to fasten its rear wall to the vehicular dashboard and its front wall to the associated master cylinder.
In commonly owned application Ser. No. 462,774 filed by us concurrently with the present application, there has been disclosed and claimed a flexible retainer which embraces the master cylinder and at least part of the periphery of the power cylinder under tension for holding same in position, this retainer passing around a free end of the master cylinder; the retainer, which may be a wire or cable but preferably is designed as a strap, advantageously has extremities that are anchored to the dashboard at opposite sides of an aperture traversed by a hub-shaped extension of the power cylinder. The retainer may be provided with adjustable braking means, interposed between a bight thereof and the free end of the master cylinder, for varying its tension and, if necessary, relaxing it sufficiently to detach its bight from the master cylinder so as to facilitate the removal of the latter from the power cylinder.